1. Field of the Invention
The present invention relates to an epoch-making slag crushing device whose length can be reduced, when slag formed in melting aluminum or an aluminum alloy is processed, by mainly crushing the slag and additionally cooling the slag effectively.
2. Description of the Prior Art
When an ingot or a block of aluminum or an aluminum alloy is melted by, for example, a melting and holding furnace, a contained metal other than aluminum or an oxide floats up on molten aluminum as slag. Since this slag still contains separable metallic aluminum in large quantities, the slag is first squeezed through the squeezing process referred to as dross squeezing and the metallic aluminum thus obtained is directly introduced into the melting and holding furnace to recover the aluminum.
However, a thermic reaction occurs in part of the slag squeezed through the above described dross squeezing. The larger a mass of slag is, the higher the temperature of the inside of the mass is (2000.degree. C. to 3000.degree. C.). If the mass is left as it is, the mass and surrounding small masses of slag coalesce to increasingly grow into a large mass of slag. Consequently, the above described thermit reaction is promoted so that the large mass of slag is hotter, contributing to a fire, for example, which is very dangerous.
In order to restrain the thermit reaction, the above described slag may be cooled. Even if the surface of the large mass of slag is merely cooled, however, it is difficult to reduce the temperature of the inside of the mass of slag.
Furthermore, even if the slag is squeezed through the dross squeezing, aluminum is, in fact, still contained in the slag. Accordingly, there has been a demand for effective recovery of this aluminum.
Additionally, besides separating the aluminum from the slag, it is also necessary to crush the slag to separate a reusable contained metal or a reusable oxide from the slag and then, discard the same.